<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>图片</title>
</head>
<body>
<img class="a" src="../img/a.gif" alt="">
<img src="../img/b.gif" class="b" alt="">
<img src="../img/c.gif" alt="响应式图片">
<style>
    .c{
        height: auto;
        width: auto;
    }
    .b{
        border: 1px solid #ddd;
        border-radius: 4px;
        padding: 5px;
    }
    .a{
        border-radius: 50%;
        padding: 10px;
    }
</style>
</body>
</html>